Casing pipe for thermal recovery of thickened oil and preparation method of casing pipe

Abstract

The invention discloses a casing pipe for heavy oil thermal recovery and a preparation method thereof, and relates to the technical field of petroleum casing pipes. The sleeve comprises the following chemical components in percentage by mass: 0.20 to 0.30 percent of C, 1.00 to 1.15 percent of Si, 1.20 to 1.33 percent of Mn, 0.60 to 0.85 percent of Cr, 0.33 to 0.48 percent of Mo, 0.03 to 0.10 percent of Nb, 0.001 to 0.004 percent of RE, 0.010 to 0.030 percent of Al, 0.012 to 0.025 percent of Ca, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.005 percent of N, less than or equal to 0.007 percent of O + H + N and the balance of Fe and inevitable impurities. The yield strength of the casing pipe at room temperature reaches the maximum 150 ksi steel grade requirement, the total elongation is greater than 23%, and the yield strength at 350 DEG C is reduced by not more than 16% of the yield strength at room temperature.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum casing, in particular to a heavy oil thermal utilization casing and a preparation method thereof. Background Art

[0002] Heavy oil accounts for a large proportion of my country's oil and gas resources. Heavy oil production usually uses circulating steam heating as the main method, and the circulating steam temperature is as high as 350°C. Due to the repeated temperature changes, the casing damage caused by the repeated cycles is very serious, including casing deformation, necking, misalignment, threaded connection disengagement, etc. The casing loss of thermal recovery wells generally exceeds 30%, and in some blocks it is even as high as 50% to 70%. In the past, the design of heavy oil thermal recovery well casing was mainly based on stress, and the strength index of the material was mainly considered; under the conditions of heavy oil thermal recovery, the casing material has creep and stress relaxation phenomena, and plastic strain fatigue will occur during the thermal cycle process. Due to the lack of full consideration of these factors, the performance of existing products is difficult to meet the performance and quality requirements of the casing under heavy oil thermal recovery conditions, which is the fundamental reason for the serious casing damage in thermal recovery wells. To solve this problem, a strain-based casing string design method for heavy oil thermal recovery wells has been developed in recent years. In addition to the strength requirements for the thermal recovery casing, it also puts forward requirements for the elongation of its uniform plastic deformation and the reduction of high-temperature mechanical properties, so as to ensure that the casing can withstand large uniform plastic deformation and plastic strain fatigue without premature failure during the heavy oil thermal recovery process.

[0003] Although a series of high-strength casing products for heavy oil thermal recovery wells have been developed, these products do not involve high-strength and high-uniform elongation thermal recovery casings based on the design concept of strain casing strings. Therefore, it is imperative to propose a casing with high strength and sufficiently uniform elongation suitable for heavy oil steam huff and puff thermal recovery. Summary of the invention

[0004] Based on the above-mentioned deficiencies of the prior art, the object of the present invention is to provide a heavy oil hot-adoption casing with high strength and sufficiently uniform elongation and a preparation method thereof.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, there is provided a heavy oil thermal utilization casing, wherein the heavy oil thermal utilization casing comprises the following chemical components by weight percentage:

[0007] C 0.20%~0.30%, Si 1.00%~1.15%, Mn 1.20%~1.33%, Cr 0.60%~0.85%, Mo 0.33%~0.48%, Nb 0.03%~0.10%, RE 0.001%~0.004%, Al 0.010%~0.030%, Ca 0.012%~0.025%, P≤0.015%, S≤0.005%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0008] Optionally, the heavy oil heat utilization casing includes the following chemical components in terms of mass percentage:

[0009] C 0.20%~0.22%, Si 1.00%~1.02%, Mn 1.20%~1.22%, Cr 0.60%~0.65%, Mo 0.33%~0.35%, Nb 0.03%~0.05%, RE 0.001%~0.002%, Al 0.010%~0.014%, Ca 0.012%~0.014%, P≤0.012%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0010] Optionally, the heavy oil heat utilization casing includes the following chemical components in terms of mass percentage:

[0011] C 0.21%~0.23%, Si 1.03%~1.05%, Mn 1.21%~1.23%, Cr 0.66%~0.69%, Mo 0.34%~0.36%, Nb 0.04%~0.06%, RE 0.002%~0.003%, Al 0.015%~0.017%, Ca 0.015%~0.017%, P≤0.012%, S≤0.003%, N≤0.004%, O+H+N≤0.006%, and the balance is Fe and unavoidable impurities.

[0012] Optionally, the heavy oil heat utilization casing includes the following chemical components in terms of mass percentage:

[0013] C 0.21%~0.24%, Si 1.05%~1.08%, Mn 1.22%~1.24%, Cr 0.71%~0.75%, Mo 0.37%~0.39%, Nb 0.05%~0.07%, RE 0.002%~0.003%, Al 0.018%~0.020%, Ca 0.016%~0.018%, P≤0.011%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0014] Optionally, the heavy oil heat utilization casing includes the following chemical components in terms of mass percentage:

[0015] C 0.23%~0.25%, Si 1.09%~1.11%, Mn 1.25%~1.27%, Cr 0.76%~0.79%, Mo 0.40%~0.42%, Nb 0.06%~0.08%, RE 0.003%~0.004%, Al 0.021%~0.024%, Ca 0.018%~0.020%, P≤0.012%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0016] Optionally, the heavy oil heat utilization casing includes the following chemical components in terms of mass percentage:

[0017] C 0.25%~0.27%, Si 1.12%~1.14%, Mn 1.28%~1.30%, Cr 0.81%~0.83%, Mo 0.43%~0.45%, Nb 0.07%~0.09%, RE 0.003%, Al 0.025%~0.027%, Ca0.021%~0.023%, P≤0.011%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0018] Optionally, the heavy oil heat utilization casing includes the following chemical components in terms of mass percentage:

[0019] C 0.28%~0.30%, Si 1.13%~1.15%, Mn 1.31%~1.33%, Cr 0.83%~0.85%, Mo 0.46%~0.48%, Nb 0.08%~0.10%, RE 0.004%, Al 0.028%~0.030%, Ca0.023%~0.025%, P≤0.010%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0020] A second aspect of the present invention provides a method for preparing a heavy oil thermal utilization casing, which comprises the steps of:

[0021] According to the present invention, the chemical composition of the heavy oil heat-using casing is batched, smelted, and continuously cast to obtain a continuous casting billet;

[0022] The continuous casting billet is subjected to hot piercing and hot continuous rolling to obtain a tube billet;

[0023] The tube blank is subjected to tempering heat treatment, heat straightening and then thread processing to obtain the heavy oil hot-using casing.

[0024] Optionally, after smelting and continuous casting, a continuous casting billet is obtained; and after hot perforating and hot rolling the continuous casting billet, a step of obtaining a tube billet specifically includes:

[0025] The raw materials obtained by batching are successively subjected to oxygen-blown converter smelting, RE wire feeding, external refining, vacuum degassing, and Si-Ca wire feeding for modification of inclusions to obtain molten steel;

[0026] Casting the molten steel into a rod-shaped continuous casting billet;

[0027] The continuous casting billet is heated to 1180-1230° C. in a heating furnace, kept warm for 90-120 minutes, then hot-pierced at 1170-1200° C., hot-rolled at 950-1150° C., and cooled to obtain a tube billet.

[0028] Optionally, the step of subjecting the tube blank to tempering heat treatment, heat straightening, and then threading to obtain the heavy oil hot-adopting casing specifically includes:

[0029] In a protective atmosphere furnace, the tube blank is heated at a temperature of 890-910° C., kept warm for 40-60 minutes, and then cooled by internal and external water spraying at a cooling rate of 30° C. / s or more. Then, it is tempered at a temperature of 585-640° C. for 90-120 minutes and then water-cooled. Then, it is hot straightened at a temperature of 530-590° C. and then water-cooled. After thread processing, the heavy oil hot adopting casing is obtained.

[0030] Beneficial effects: The heavy oil thermal recovery casing provided by the present invention has excellent comprehensive performance, high strength and sufficiently large elongation, and the room temperature yield strength can reach the steel grade requirements of 120ksi, 125ksi, 130ksi, 135ksi, 140ksi and 150ksi respectively, that is, the minimum room temperature yield strength is greater than 827-1034MPa, the minimum tensile strength is greater than 965-1172MPa, the total elongation is greater than or equal to 23%, the uniform elongation is greater than or equal to 12%, and the Charpy V-notch impact toughness at 0°C is greater than or equal to 100J. The yield strength at 350°C decreases by no more than 16% of the room temperature yield strength, which can meet the requirements of 350°C heavy oil steam thermal recovery deep wells for casing strength, plasticity and strain fatigue life. DETAILED DESCRIPTION

[0031] The present invention provides a heavy oil thermal utilization casing and a preparation method thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] The embodiment of the present invention provides a heavy oil thermal utilization casing, wherein the heavy oil thermal utilization casing comprises the following chemical components by weight percentage:

[0034] C 0.20%~0.30%, Si 1.00%~1.15%, Mn 1.20%~1.33%, Cr 0.60%~0.85%, Mo 0.33%~0.48%, Nb 0.03%~0.10%, RE 0.001%~0.004%, Al 0.010%~0.030%, Ca 0.012%~0.025%, P≤0.015%, S≤0.005%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0035] RE is a rare earth element. In some specific embodiments, RE may be Ce (cerium).

[0036] In terms of component design, the embodiment of the present invention intends to adopt a low C content, add Si, Mn, Cr, Mo, Nb micro-alloying, and add rare earth (RE) elements, control harmful elements such as P, S, O, H, N in the steel, use Al and Si fully deoxidized calm steel, and perform Ca treatment on the molten steel to achieve the comprehensive performance requirements of heavy oil thermal recovery casing that take into account high strength and sufficiently uniform elongation. The present invention designs the chemical composition and content of the heavy oil thermal use casing so that the elements produce synergistic effects, and finally the heavy oil thermal use casing has high strength and sufficiently large elongation, and has excellent comprehensive performance. The room temperature yield strength can reach the requirements of 120ksi, 125ksi, 130ksi, 135ksi, 140ksi and 150ksi steel grades respectively, that is, the room temperature minimum yield strength is greater than 827-1034MPa, the minimum tensile strength is greater than 965-1172MPa, the total elongation is greater than or equal to 23%, the uniform elongation is greater than or equal to 12%, and the Charpy V-notch impact toughness at 0°C is greater than or equal to 100J. The yield strength at 350°C decreases by no more than 16% of the room temperature yield strength, and can meet the requirements of 350°C heavy oil steam thermal recovery deep well on casing strength, plasticity and strain fatigue life, and can meet the requirements that the casing can withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process.

[0037] Among them, C is the main strengthening element in steel. If the C content is too low, it is not conducive to improving the hardenability of steel and the strength of steel; if the C content is too high, it is not conducive to the plasticity and toughness of steel. Considering comprehensively, it is advisable to control it within the range of 0.20% to 0.30%.

[0038] Si is mainly used to improve the strength, oxidation resistance and thermal fatigue resistance of steel. Taking all factors into consideration, it is advisable to control it within the range of 1.00% to 1.15%.

[0039] Mn is mainly used to improve the hardenability of steel, thereby increasing strength, but too high a content will increase the tendency of segregation. Taking all factors into consideration, it is advisable to control it within the range of 1.20% to 1.33%.

[0040] Cr is mainly used to improve the hardenability of steel, thereby improving strength, oxidation resistance and corrosion resistance, but too high a content will increase the cost. Taking all factors into consideration, it is advisable to control it within the range of 0.60% to 0.85%.

[0041] Mo is mainly used to improve the hardenability of steel to improve strength and tempering stability, while improving corrosion resistance, but too high a content will increase costs. Taking all factors into consideration, it is advisable to control it within the range of 0.33% to 0.48%.

[0042] Nb is added to steel to form NbC and NbN with C and N in steel respectively, which has the effect of hindering the growth of austenite grains and refining grains, thereby improving strength and toughness. Taking all factors into consideration, it is advisable to control it within the range of 0.03% to 0.10%.

[0043] A small amount of RE (rare earth element) can purify molten steel, modify inclusions, and alloy, which is beneficial to improving the strength and plasticity of steel. Too low a content will not play the role it should play, and too high a content will easily cause new inclusions and increase costs. Considering all factors, it is advisable to control it within the range of 0.001% to 0.004%.

[0044] Al is an important deoxidizer. Al forms oxides with oxygen to deoxidize, and forms nitrides with nitrogen to partially eliminate the adverse effects of N. It also refines grains and improves strength and toughness. To ensure the effect of N control, Al / N ≥ 2 (i.e., the ratio of Al mass percentage to N mass percentage is greater than or equal to 2) is required. Taking all factors into consideration, the Al content should be controlled within the range of 0.010% to 0.030%.

[0045] Ca can improve the properties and morphology of inclusions, thereby improving the plasticity, toughness and corrosion resistance of steel. To ensure the deformation control effect of inclusions, it is necessary to control Ca / S≥2 (that is, the ratio of Ca mass percentage to S mass percentage is greater than or equal to 2). Taking all factors into consideration, the Ca content should be controlled within the range of 0.012% to 0.025%.

[0046] P is a harmful element that mainly affects the plasticity and toughness of steel. Taking all factors into consideration, it is advisable to control P ≤ 0.015% (i.e. the mass content of P is less than or equal to 0.015%).

[0047] S is a harmful element that mainly affects the plasticity and toughness of steel. Taking all factors into consideration, it is advisable to control S ≤ 0.005% (i.e. the mass content of S is less than or equal to 0.005%).

[0048] O is a harmful element, which mainly affects the plastic toughness of steel. H is a harmful element, which mainly affects the plastic toughness of steel. N is a harmful element, which mainly affects the plastic toughness strain aging performance of steel. Taking all factors into consideration, it is advisable to control N≤0.005% (i.e. the mass content of N is less than or equal to 0.005%). And control O+H+N≤0.007% (i.e. the sum of the mass content of O, H and N is less than or equal to 0.007%).

[0049] In some embodiments, the heavy oil heat utilization casing comprises the following chemical components by weight percentage:

[0050] C 0.20%~0.22%, Si 1.00%~1.02%, Mn 1.20%~1.22%, Cr 0.60%~0.65%, Mo 0.33%~0.35%, Nb 0.03%~0.05%, RE 0.001%~0.002%, Al 0.010%~0.014%, Ca 0.012%~0.014%, P≤0.012%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0051] In this embodiment, the yield strength level of the heavy oil thermal recovery casing can reach the requirement of 120ksi. Among them, at room temperature, the yield strength reaches 880-885MPa, the tensile strength reaches 989-994MPa, the total elongation reaches 26%, and the uniform elongation reaches 15%; the Charpy impact toughness at 0°C reaches 120-122J; at 350°C, the yield strength reaches 748-752MPa, the tensile strength reaches 870-875MPa, the total elongation reaches 29%, and the uniform elongation reaches 17%. At 350°C, the yield strength decreases by no more than 16% of the room temperature yield strength, which can meet the requirements of the casing to withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process, and meet the requirements of 350°C heavy oil steam thermal recovery wells for casing strength and strain fatigue life.

[0052] In some embodiments, the heavy oil heat utilization casing comprises the following chemical components by weight percentage:

[0053] C 0.21%~0.23%, Si 1.03%~1.05%, Mn 1.21%~1.23%, Cr 0.66%~0.69%, Mo 0.34%~0.36%, Nb 0.04%~0.06%, RE 0.002%~0.003%, Al 0.015%~0.017%, Ca 0.015%~0.017%, P≤0.012%, S≤0.003%, N≤0.004%, O+H+N≤0.006%, and the balance is Fe and unavoidable impurities.

[0054] In this embodiment, the yield strength level of the heavy oil thermal recovery casing can reach the requirement of 125ksi. Among them, at room temperature, the yield strength reaches 915-920MPa, the tensile strength reaches 1028-1034MPa, the total elongation reaches 25.4%-25.6%, and the uniform elongation reaches 14.4%-14.6%; the Charpy impact toughness at 0°C reaches 116-119J; at 350°C, the yield strength reaches 778-782MPa, the tensile strength reaches 905-910MPa, the total elongation reaches 28.3%-28.5%, and the uniform elongation reaches 16.3%-16.6%. At 350°C, the yield strength decreases by no more than 16% of the room temperature yield strength, which can meet the requirements that the casing can withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process, and meet the requirements of 350°C heavy oil steam thermal recovery wells for casing strength and strain fatigue life.

[0055] In some embodiments, the heavy oil heat utilization casing comprises the following chemical components by weight percentage:

[0056] C 0.21%~0.24%, Si 1.05%~1.08%, Mn 1.22%~1.24%, Cr 0.71%~0.75%, Mo 0.37%~0.39%, Nb 0.05%~0.07%, RE 0.002%~0.003%, Al 0.018%~0.020%, Ca 0.016%~0.018%, P≤0.011%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0057] In this embodiment, the yield strength level of the heavy oil thermal recovery casing can reach the requirement of 130ksi. Among them, at room temperature, the yield strength reaches 949-955MPa, the tensile strength reaches 1066-1073MPa, the total elongation reaches 25%, and the uniform elongation reaches 14%; the Charpy impact toughness at 0°C reaches 113-115J; at 350°C, the yield strength reaches 807-812MPa, the tensile strength reaches 938-944MPa, the total elongation reaches 28%, and the uniform elongation reaches 16%. At 350°C, the yield strength decreases by no more than 16% of the room temperature yield strength, which can meet the requirements of the casing to withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process, and meet the requirements of 350°C heavy oil steam thermal recovery wells for casing strength and strain fatigue life.

[0058] In some embodiments, the heavy oil heat utilization casing comprises the following chemical components by weight percentage:

[0059] C 0.23%~0.25%, Si 1.09%~1.11%, Mn 1.25%~1.27%, Cr 0.76%~0.79%, Mo 0.40%~0.42%, Nb 0.06%~0.08%, RE 0.003%~0.004%, Al 0.021%~0.024%, Ca 0.018%~0.020%, P≤0.012%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0060] In this embodiment, the yield strength level of the heavy oil thermal recovery casing can reach the requirement of 135ksi. Among them, at room temperature, the yield strength reaches 984-989MPa, the tensile strength reaches 1106-1111MPa, the total elongation reaches 24.5%-24.6%, and the uniform elongation reaches 13.4%-13.6%; the Charpy impact toughness at 0°C reaches 108-110J; at 350°C, the yield strength reaches 836-841MPa, the tensile strength reaches 973-978MPa, the total elongation reaches 27.4%-27.6%, and the uniform elongation reaches 15.4%-15.7%. At 350°C, the yield strength decreases by no more than 16% of the room temperature yield strength, which can meet the requirements of the casing to withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process, and meet the requirements of the 350°C heavy oil steam thermal recovery well for casing strength and strain fatigue life.

[0061] In some embodiments, the heavy oil heat utilization casing comprises the following chemical components by weight percentage:

[0062] C 0.25%~0.27%, Si 1.12%~1.14%, Mn 1.28%~1.30%, Cr 0.81%~0.83%, Mo 0.43%~0.45%, Nb 0.07%~0.09%, RE 0.003%, Al 0.025%~0.027%, Ca0.021%~0.023%, P≤0.011%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0063] In this embodiment, the yield strength level of the heavy oil thermal recovery casing can reach the requirement of 140ksi. Among them, at room temperature, the yield strength reaches 1018-1024MPa, the tensile strength reaches 1131-1138MPa, the total elongation reaches 24%, and the uniform elongation reaches 13%; the Charpy impact toughness at 0°C reaches 105-108J; at 350°C, the yield strength reaches 865-870MPa, the tensile strength reaches 995-1001MPa, the total elongation reaches 27%, and the uniform elongation reaches 15%. At 350°C, the yield strength decreases by no more than 16% of the room temperature yield strength, which can meet the requirements of the casing to withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process, and meet the requirements of 350°C heavy oil steam thermal recovery wells for casing strength and strain fatigue life.

[0064] In some embodiments, the heavy oil heat utilization casing comprises the following chemical components by weight percentage:

[0065] C 0.28%~0.30%, Si 1.13%~1.15%, Mn 1.31%~1.33%, Cr 0.83%~0.85%, Mo 0.46%~0.48%, Nb 0.08%~0.10%, RE 0.004%, Al 0.028%~0.030%, Ca0.023%~0.025%, P≤0.010%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

[0066] In this embodiment, the yield strength level of the heavy oil thermal recovery casing can reach the requirement of 150ksi. Among them, at room temperature, the yield strength reaches 1087-1093MPa, the tensile strength reaches 1208-1214MPa, the total elongation reaches 23%, and the uniform elongation reaches 12%; the Charpy impact toughness at 0°C reaches 101-104J; at 350°C, the yield strength reaches 924-929MPa, the tensile strength reaches 1063-1068MPa, the total elongation reaches 26%, and the uniform elongation reaches 14%. At 350°C, the yield strength decreases by no more than 16% of the room temperature yield strength, which can meet the requirements of the casing to withstand large uniform plastic deformation and plastic strain fatigue without early damage during the heavy oil thermal recovery process, and meet the requirements of the 350°C heavy oil steam thermal recovery well for casing strength and strain fatigue life.

[0067] The present invention develops a manufacturing process that matches the chemical composition of the above-mentioned proportion content, mainly through steelmaking (including refining outside the furnace, vacuum degassing, Ca treatment), continuous casting, hot rolling in the austenite zone, tempering heat treatment, heat straightening, non-destructive testing and other processes, so that the material obtains a fine and uniform microstructure to achieve a reasonable match between the strength and plasticity and toughness of the casing. Specifically, an embodiment of the present invention also provides a method for preparing a heavy oil hot-adopting casing, comprising the steps of:

[0068] S1. According to the embodiment of the present invention, the chemical composition of the heavy oil hot-using casing is batched, smelted, and continuously cast to obtain a continuous casting billet;

[0069] S2, hot piercing and hot rolling the continuous casting billet to obtain a tube billet;

[0070] S3, subjecting the tube blank to tempering heat treatment, heat straightening and then thread processing to obtain the heavy oil hot-using casing.

[0071] The chemical composition design and manufacturing process coordination of the embodiment of the present invention have the effects of increasing strength and improving plasticity and toughness.

[0072] The preparation method of the present invention is aimed at the heavy oil thermal adoption casing with the above chemical composition, obtains the expected organizational structure and performance, gives full play to the performance of the heavy oil thermal adoption casing, has low cost, and the process parameters in the process are easy to control, and the obtained heavy oil thermal adoption casing has stable performance.

[0073] In step S1, in some embodiments, after smelting and continuous casting, the step of obtaining the continuous casting billet specifically includes:

[0074] The raw materials obtained by batching are successively subjected to oxygen-blown converter smelting, feeding RE wire (such as Ce wire), external refining, vacuum degassing, and feeding Si-Ca wire to denature inclusions to obtain molten steel;

[0075] The molten steel is cast into a rod-shaped continuous casting billet (electromagnetic stirring and soft reduction techniques can be used during the continuous casting process to control segregation in the continuous casting billet).

[0076] In step S2, in some embodiments, the step of obtaining a tube billet after hot piercing and hot rolling the continuous casting billet specifically includes:

[0077] The continuous casting billet is heated to 1180-1230°C in a heating furnace, kept warm for 90-120 minutes, then hot-pierced at 1170-1200°C, hot-rolled at 950-1150°C, and cooled (for example, air-cooled) to obtain a tube billet (specifically, it can be sawed to a suitable length to obtain a tube billet).

[0078] In step S3, in some embodiments, the step of subjecting the tube blank to tempering heat treatment, heat straightening and then threading to obtain the heavy oil hot-adopting casing specifically includes:

[0079] In a protective atmosphere furnace, the tube blank is heated at a temperature of 890-910° C., kept at this temperature for 40-60 minutes, and then cooled by spraying water inside and outside at a cooling rate of 30° C. / s or more (e.g., 30-60° C. / s) to obtain a martensitic structure; then, it is tempered at a temperature of 585-640° C. for 90-120 minutes and then water-cooled (water cooling after tempering to avoid possible temper brittleness) to obtain a tempered bainite structure; then, it is hot straightened at a temperature of 530-590° C. and then water-cooled, and threaded (non-destructive testing can be performed before threading) to obtain the heavy oil hot adopting casing.

[0080] Specifically, according to actual needs, API standard threads or special threads can be processed at both ends of the pipe section, and the threads can be subjected to magnetic particle inspection.

[0081] The present invention will be further described below by means of specific examples.

[0082] Example 1

[0083] Table 1 Chemical composition of heavy oil heat-using casing in Examples 1-18

[0084]

[0085] In Examples 1-18 in Table 1, the content of each component is in mass percentage, and the remainder to 100% is Fe and unavoidable impurities.

[0086] Example 1

[0087] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0088] Steelmaking: The ingredients are prepared according to the composition of the heavy oil hot-using casing of Example 1 shown in Table 1, and then steelmaking is carried out in oxygen-blown converter, Ce wire is fed, refining outside the furnace, vacuum degassing, and Si-Ca wire is fed to control deformation of inclusions to obtain molten steel;

[0089] Continuous casting: The molten steel is cast into rod-shaped continuous casting billets. During the continuous casting process, electromagnetic stirring and soft pressure reduction technology are used to control the segregation in the continuous casting billets;

[0090] Piercing and hot rolling: The continuous casting billet is heated in a ring heating furnace at a temperature of 1200°C for 120 minutes, then hot-pierced at 1170°C, hot-rolled at 950°C to 1150°C (the initial rolling temperature is 1150°C and the final rolling temperature is 950°C), air-cooled, and sawed to a preset length to obtain a tube billet;

[0091] Quenching and tempering heat treatment, heat straightening: adopt the heat treatment process of heating in a protective atmosphere furnace, quenching + high temperature tempering, in the protective atmosphere furnace, heat the tube blank at a temperature of 900°C, keep it warm for 60 minutes, and then spray water inside and outside at a cooling rate of 30°C / s to obtain a martensitic structure; then temper it at a temperature of 640°C, the tempering time is 120 minutes, so as to obtain fine and uniform tempered troostite, and water cool it after tempering; then heat straighten it at a temperature of 590°C and then water cool it; after thread processing, the heavy oil hot oil casing is obtained.

[0092] Example 2

[0093] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0094] Steelmaking: The difference from Example 1 is that the ingredients are prepared according to the composition of the heavy oil heat-using casing of Example 2 shown in Table 1;

[0095] Continuous casting: same as in Example 1;

[0096] Piercing and hot rolling: same as in Example 1;

[0097] Tempering heat treatment and heat straightening: same as in Example 1.

[0098] Example 3

[0099] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0100] Steelmaking: The difference from Example 1 is that the ingredients are prepared according to the composition of the heavy oil heat-using casing of Example 3 shown in Table 1;

[0101] Continuous casting: same as in Example 1;

[0102] Piercing and hot rolling: same as in Example 1;

[0103] Tempering heat treatment and heat straightening: same as in Example 1.

[0104] Example 4

[0105] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0106] Steelmaking: The only difference from Example 1 is that the heavy oil heat-using casing of Example 4 is batched according to the composition shown in Table 1;

[0107] Continuous casting: same as in Example 1;

[0108] Piercing and hot rolling: same as in Example 1;

[0109] Quenching and tempering heat treatment, heat straightening: The only difference from Example 1 is that tempering is performed at a temperature of 630°C; and heat straightening is performed at a temperature of 580°C.

[0110] Example 5

[0111] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0112] Steelmaking: The only difference from Example 4 is that the heavy oil heat-using casing of Example 5 is batched according to the composition shown in Table 1;

[0113] Continuous casting: same as in Example 4;

[0114] Piercing and hot rolling: same as in Example 4;

[0115] Tempering heat treatment and heat straightening: same as in Example 4.

[0116] Example 6

[0117] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0118] Steelmaking: The only difference from Example 4 is that the heavy oil heat-using casing of Example 6 is batched according to the composition shown in Table 1;

[0119] Continuous casting: same as in Example 4;

[0120] Piercing and hot rolling: same as in Example 4;

[0121] Tempering heat treatment and heat straightening: same as in Example 4.

[0122] Example 7

[0123] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0124] Steelmaking: The only difference from Example 1 is that the heavy oil heat-using casing of Example 7 is batched according to the composition shown in Table 1;

[0125] Continuous casting: same as in Example 1;

[0126] Piercing and hot rolling: same as in Example 1;

[0127] Tempering heat treatment and heat straightening: The only difference from Example 1 is that tempering is performed at a temperature of 620°C; and heat straightening is performed at a temperature of 570°C.

[0128] Example 8

[0129] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0130] Steelmaking: The only difference from Example 7 is that the heavy oil heat-using casing of Example 8 is batched according to the composition shown in Table 1;

[0131] Continuous casting: same as in Example 7;

[0132] Piercing and hot rolling: same as in Example 7;

[0133] Tempering heat treatment and heat straightening: same as Example 7.

[0134] Example 9

[0135] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0136] Steelmaking: The only difference from Example 7 is that the heavy oil heat-using casing of Example 9 is batched according to the composition shown in Table 1;

[0137] Continuous casting: same as in Example 7;

[0138] Piercing and hot rolling: same as in Example 7;

[0139] Tempering heat treatment and heat straightening: same as Example 7.

[0140] Example 10

[0141] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0142] Steelmaking: The only difference from Example 1 is that the heavy oil heat-using casing of Example 10 is batched according to the composition shown in Table 1;

[0143] Continuous casting: same as in Example 1;

[0144] Piercing and hot rolling: same as in Example 1;

[0145] Quenching and tempering heat treatment, heat straightening: The only difference from Example 1 is that tempering is performed at a temperature of 610°C; and heat straightening is performed at a temperature of 560°C.

[0146] Embodiment 11

[0147] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0148] Steelmaking: The only difference from Example 10 is that the heavy oil heat-using casing of Example 11 is batched according to the composition shown in Table 1;

[0149] Continuous casting: same as in Example 10;

[0150] Piercing and hot rolling: same as in Example 10;

[0151] Tempering heat treatment and heat straightening: same as Example 10.

[0152] Example 12

[0153] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0154] Steelmaking: The only difference from Example 10 is that the heavy oil heat-using casing of Example 12 is batched according to the composition shown in Table 1;

[0155] Continuous casting: same as in Example 10;

[0156] Piercing and hot rolling: same as in Example 10;

[0157] Tempering heat treatment and heat straightening: same as Example 10.

[0158] Embodiment 13

[0159] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0160] Steelmaking: The only difference from Example 1 is that the heavy oil heat-using casing of Example 13 is batched according to the composition shown in Table 1;

[0161] Continuous casting: same as in Example 1;

[0162] Piercing and hot rolling: same as in Example 1;

[0163] Quenching and tempering heat treatment, heat straightening: The only difference from Example 1 is that tempering is performed at a temperature of 600°C; and heat straightening is performed at a temperature of 550°C.

[0164] Embodiment 14

[0165] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0166] Steelmaking: The only difference from Example 13 is that the heavy oil heat-using casing of Example 14 is batched according to the composition shown in Table 1;

[0167] Continuous casting: same as in Example 13;

[0168] Piercing and hot rolling: same as in Example 13;

[0169] Tempering heat treatment and heat straightening: same as Example 13.

[0170] Embodiment 15

[0171] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0172] Steelmaking: The only difference from Example 13 is that the heavy oil heat-using casing of Example 15 is batched according to the composition shown in Table 1;

[0173] Continuous casting: same as in Example 13;

[0174] Piercing and hot rolling: same as in Example 13;

[0175] Tempering heat treatment and heat straightening: same as Example 13.

[0176] Example 16

[0177] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0178] Steelmaking: The only difference from Example 1 is that the heavy oil heat-using casing of Example 16 is batched according to the composition shown in Table 1;

[0179] Continuous casting: same as in Example 1;

[0180] Piercing and hot rolling: same as in Example 1;

[0181] Tempering heat treatment and heat straightening: The only difference from Example 1 is that tempering is performed at a temperature of 585°C; and heat straightening is performed at a temperature of 530°C.

[0182] Embodiment 17

[0183] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0184] Steelmaking: The only difference from Example 16 is that the heavy oil heat-using casing of Example 17 is batched according to the composition shown in Table 1;

[0185] Continuous casting: same as in Example 16;

[0186] Piercing and hot rolling: same as in Example 16;

[0187] Tempering heat treatment and heat straightening: same as Example 16.

[0188] Embodiment 18

[0189] A method for preparing a heavy oil hot-using petroleum casing comprises the following steps:

[0190] Steelmaking: The only difference from Example 16 is that the heavy oil heat-using casing of Example 18 is batched according to the composition shown in Table 1;

[0191] Continuous casting: same as Example 16;

[0192] Piercing and hot rolling: same as in Example 16;

[0193] Tempering heat treatment and heat straightening: same as Example 16.

[0194] The heavy oil hot-adoption sleeves prepared in Examples 1-18 were subjected to tensile property tests at room temperature and 350°C, including yield strength test, tensile strength test, total elongation test, uniform elongation test and Charpy V-notch impact toughness test at 0°C. The results are shown in Tables 2 and 3 below.

[0195] Table 2. Room temperature tensile properties and impact toughness at 0°C of the heavy oil hot-use casing prepared in Examples 1-18

[0196]

[0197]

[0198] Table 3. Tensile properties of the heavy oil hot-use casing prepared in Examples 1-18 at 350°C

[0199]

[0200]

[0201] In the table, 120SH, 125SH, 130SH, 135SH, 140SH and 150SH correspond to steel grades of 120ksi, 125ksi, 130ksi, 135ksi, 140ksi and 150ksi casing respectively.

[0202] The above results show that the heavy oil heat-using casing provided by the present invention has high strength and sufficient elongation, and has excellent comprehensive properties, as follows:

[0203] At room temperature, the yield strength of 120SH heavy oil hot-dip casing is 880-885MPa, the tensile strength is 989-994MPa, the yield strength ratio is 0.89, the total elongation is 26%, the uniform elongation is 15%; the Charpy V-notch impact toughness at 0℃ is 120-122J.

[0204] At room temperature, the yield strength of 125SH heavy oil hot-dip casing is 915-920MPa, the tensile strength is 1028-1034MPa, the yield strength ratio is 0.89, the total elongation is 25.4%-25.6%, the uniform elongation is 14.4%-14.6%; the Charpy V-notch impact toughness at 0℃ is 116-119J.

[0205] At room temperature, the yield strength of 130SH heavy oil hot-dip casing is 949-955MPa, the tensile strength is 1066-1073MPa, the yield strength ratio is 0.89, the total elongation is 25%, the uniform elongation is 14%; the Charpy V-notch impact toughness at 0℃ is 113-115J.

[0206] At room temperature, the yield strength of 135SH heavy oil hot-dip casing is 984-989MPa, the tensile strength is 1106-1111MPa, the yield strength ratio is 0.89, the total elongation is 24.5%-24.6%, the uniform elongation is 13.4%-13.6%; the Charpy V-notch impact toughness at 0℃ is 108-110J.

[0207] At room temperature, the yield strength of 140SH heavy oil hot-dip casing is 1018-1024MPa, the tensile strength is 1131-1138MPa, the yield strength ratio is 0.90, the total elongation is 24%, the uniform elongation is 13%; the Charpy V-notch impact toughness at 0℃ is 105-108J.

[0208] At room temperature, the yield strength of 150SH heavy oil hot-dip casing is 1087-1093MPa, the tensile strength is 1208-1214MPa, the yield strength ratio is 0.90, the total elongation is 23%, the uniform elongation is 12%; the Charpy V-notch impact toughness at 0℃ is 101-104J.

[0209] The yield strength of the heavy oil thermal recovery casing in each embodiment at 350°C is reduced by about 15% compared with that at room temperature, and the tensile strength is reduced by about 12%, meeting the requirement of the relevant standard that the strength reduction does not exceed 20%. The yield strength ratio is further reduced, the total elongation and uniform elongation are increased, and the safety of use is improved. The requirements of heavy oil steam thermal recovery wells for casing strength, plasticity and strain fatigue life can be met.

[0210] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A heavy oil heat utilization casing, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.20%~0.30%, Si 1.00%~1.15%, Mn 1.20%~1.33%, Cr 0.60%~0.85%, Mo0.33%~0.48%, Nb 0.03%~0.10%, RE 0.001%~0.004%, Al 0.010%~0.030%, Ca0.012%~0.025%, P≤0.015%, S≤0.005%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

2. The heavy oil heat utilization casing according to claim 1, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.20%~0.22%, Si 1.00%~1.02%, Mn 1.20%~1.22%, Cr 0.60%~0.65%, Mo0.33%~0.35%, Nb 0.03%~0.05%, RE 0.001%~0.002%, Al 0.010%~0.014%, Ca0.012%~0.014%, P≤0.012%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

3. The heavy oil heat utilization casing according to claim 1, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.21%~0.23%, Si 1.03%~1.05%, Mn 1.21%~1.23%, Cr 0.66%~0.69%, Mo0.34%~0.36%, Nb 0.04%~0.06%, RE 0.002%~0.003%, Al 0.015%~0.017%, Ca0.015%~0.017%, P≤0.012%, S≤0.003%, N≤0.004%, O+H+N≤0.006%, the balance is Fe and unavoidable impurities.

4. The heavy oil heat utilization casing according to claim 1, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.21%~0.24%, Si 1.05%~1.08%, Mn 1.22%~1.24%, Cr 0.71%~0.75%, Mo0.37%~0.39%, Nb 0.05%~0.07%, RE 0.002%~0.003%, Al 0.018%~0.020%, Ca0.016%~0.018%, P≤0.011%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

5. The heavy oil heat utilization casing according to claim 1, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.23%~0.25%, Si 1.09%~1.11%, Mn 1.25%~1.27%, Cr 0.76%~0.79%, Mo0.40%~0.42%, Nb 0.06%~0.08%, RE 0.003%~0.004%, Al 0.021%~0.024%, Ca0.018%~0.020%, P≤0.012%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

6. The heavy oil heat utilization casing according to claim 1, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.25%~0.27%, Si 1.12%~1.14%, Mn 1.28%~1.30%, Cr 0.81%~0.83%, Mo0.43%~0.45%, Nb 0.07%~0.09%, RE 0.003%, Al 0.025%~0.027%, Ca0.021%~0.023%, P≤0.011%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

7. The heavy oil heat utilization casing according to claim 1, characterized in that: Calculated by mass percentage, the heavy oil heat-using casing includes the following chemical components: C 0.28%~0.30%, Si 1.13%~1.15%, Mn 1.31%~1.33%, Cr 0.83%~0.85%, Mo0.46%~0.48%, Nb 0.08%~0.10%, RE 0.004%, Al 0.028%~0.030%, Ca0.023%~0.025%, P≤0.010%, S≤0.003%, N≤0.005%, O+H+N≤0.007%, and the balance is Fe and unavoidable impurities.

8. A method for preparing a heavy oil thermal utilization casing, characterized in that: Includes steps: After the chemical composition of the heavy oil hot-using casing according to any one of claims 1 to 7 is batched, smelted and continuously cast, a continuous casting billet is obtained; The continuous casting billet is subjected to hot piercing and hot continuous rolling to obtain a tube billet; The tube blank is subjected to tempering heat treatment, heat straightening and then thread processing to obtain the heavy oil hot-using casing.

9. The preparation method according to claim 8, characterized in that: After smelting and continuous casting, a continuous casting billet is obtained; after hot piercing and hot rolling the continuous casting billet, a tube billet is obtained. The steps specifically include: The raw materials obtained by batching are successively subjected to oxygen-blown converter smelting, RE wire feeding, external refining, vacuum degassing, and Si-Ca wire feeding for modification of inclusions to obtain molten steel; Casting the molten steel into a rod-shaped continuous casting billet; The continuous casting billet is heated to 1180-1230° C. in a heating furnace, kept warm for 90-120 minutes, then hot-pierced at 1170-1200° C., hot-rolled at 950-1150° C., and cooled to obtain a tube billet.

10. The preparation method according to claim 8, characterized in that: The steps of subjecting the tube blank to tempering heat treatment, heat straightening and then threading to obtain the heavy oil hot-using casing specifically include: In a protective atmosphere furnace, the tube blank is heated at a temperature of 890-910° C., kept warm for 40-60 minutes, and then cooled by internal and external water spraying at a cooling rate of greater than or equal to 30° C. / s, and then tempered at a temperature of 585-640° C. for 90-120 minutes and then water-cooled, and then hot straightened at a temperature of 530-590° C. and then water-cooled, and threaded to obtain the heavy oil hot adopting casing.

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